Sierra Dawn Thomas may have made it to the jury on Survivor: Game Changers, but it was a "rookie move" that kept her from winning the million.

In an attempt to solidify her alliance with Sarah, Thomas told her all about her legacy advantage, which she could use as immunity when six castaways remained, unless she was voted out, in which case she could leave it for another player to use. Sarah quickly took note of the second condition of the advantage, deciding to vote Sierra out in the hopes Sierra would still gift her the legacy (which she did).

ET spoke with Thomas on Thursday, the morning after her elimination, where she opened up about her decision to give Sarah the advantage after she voted her out, and how she became a possible target in the first place.

"I feel like [Survivor] kind of makes it look like [the moves came from] me and Brad, when honestly -- I feel like Brad would even back me up on this -- I feel like a lot of it was me," she explained. "I mean, I brought up the Malcolm [elimination], I brought up the Caleb [elimination]. There were a lot of moves that were solely my idea."

"I mean, some people can't see [all the moves I made this season], but you know, I'm doing something if everybody is out to get me constantly," she added.

As for her final move in the game, willing her legacy advantage to Sarah, Thomas said it's still a sore subject.

"It's such a rookie move!" she yelled. "I could barely watch it last night."

"I had no intentions of showing anybody, or telling anybody, that I had it. She and I had an hour conversation previous to me telling her. We were crying, we were getting emotional, and you see it all over my face as I'm telling her. I'm regretting it, I'm scared," she recalled. "I don't know why I told her."

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"It was my Hail Mary. I maybe should have stopped at, 'Hey, I have a secret advantage, and it's a hidden immunity idol,' instead of, 'If you vote me out, I'm going to give it to you.' Like, I have no idea... obviously I was starving, but I made the mistake of saying the full truth, 'When I do get voted out, I get to will it to someone,'" she continued. "I should have lied about that."

So Thomas should have kept that part a secret, but why still give the advantage to Sarah after she voted her out, instead of Brad, whom she had been working with for most of the season?

"It's kind of crazy. It all came down to one moment. The moment that I hear, 'Sierra, you're voted out of Survivor,' I look at Brad, and the look on his face is nothing. It's not shock, it's nothing. It's kind of like a blank slate. I look at Sarah, and she's almost crying, and seemed so upset," she said. "So, for that moment, I forgot about all of the relationship I had the whole game with Brad, and was like, 'He voted me out. Like, he had to do it. He voted me out. Obviously Sarah stuck true to her word, I'm going to give it to her.'"

"I obviously regret it. But me and Sarah did have a relationship. It's hard to see that, but we did. We talked every night, every morning," she shared. "I did have a connection with her, and maybe it wasn't as strong as mine and Brad's, but I felt like we did have a pretty good connection."

"The moment I got back to Ponderosa, I think it hit me, and I was just like, 'Shoot, I think I did the wrong thing,'" she added. "I mean, it's made me sick ever since, because I think something inside of me knew, but it was weird. It was just that one split moment. She played me, and played me so well, because I believed it, and that determined where [the legacy advantage] was going."

As for how Brad feels about Thomas' choice, she joked he's still giving her "crap about it."

"He's one of my very dear friends," she confessed. "I'm like, 'I'm sorry! I don't know what I was thinking. Obviously I wasn't thinking!'"

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"That obviously was my biggest downfall. I feel that is the big reason why I went home," she said. "But, I mean, I made a promise to myself from the first season to this one, that I was going to come in and play a bigger game."

"I didn't feel like I necessarily deserved to be there, so I was like, 'You know what? I'm going to shock everyone who doesn't think I deserve to be here, including myself!'" she explained. "So I maybe shouldn't have gone as hard as I did, but in my mind, I wanted to have 10 reasons, 15 reasons why I deserve a million dollars in the end. So I was like, 'I gotta make moves. I constantly have got to be playing,' whereas I maybe shouldn't have been so sassy and so extreme all the time."

Thomas -- who is rooting for Brad to make it all the way, though noted "there's just a million different things that could happen" before the season comes to a close -- would love to come back for another season to redeem herself.

"I mean, my body, it hurts from it still, but the competitor in me says yes. I see how much I changed from my first season to my second, and I can't even imagine the player I would be a third time around," she mused. "So, if given the opportunity, I think I would do it solely just because I think I would be even a better player than I was this time."